INITIATING THE FIRST DTP VACCINATION AGE-APPROPRIATELY - A MODEL FOR UNDERSTANDING VACCINATION COVERAGE

Objective. Our earlier research found that the strongest predictor of not being up to date on the full series of immunizations by 24 months is failure to receive the first diphtheria vaccine and tetanus toroid and pertussis vaccine (DTP1) on time. To learn more about the relation ship between successful vaccination during the DTP1 age-appropriate (D TP1-AA) period (between 42 and 92 days of life, inclusive) and an infa nt's early visit to the physician (before 42 days of life), we quantif ied children's progression through a sequence of provider visits and o utcomes. Design. This study analyzed data from 426 children living in the 57 poorest census tracts in Baltimore. For each DTP1-AA visit, we calculated the percentage of times a DTP1-AA vaccination, provider mis sed opportunity, or deferral for a valid contraindication occurred. Re lative and attributable risks were computed to assess associations bet ween DTP1-AA vaccination and early visits and missed opportunities. Re sults. We found the following: 1) Children who made a visit before 42 days of life were more than twice as likely to receive a DTP1-AA vacci nation; 2) the missed opportunity rate for children who did not make a n early visit was approximately twice that of the early-visit group; a nd 3) well visits were more likely to result in DTP1-AA immunization t han sick visits. Attributable risk calculations show that DTP1-AA vacc ination rates could be increased in this population by one third if al l infants had an early visit. Conclusions. Early in-office visits seem to make DTP1-AA vaccination more likely. These rates may be amenable to intervention by increasing early visits and reducing DTP1-AA missed opportunities. Introduction of the hepatitis B vaccine to the recomme nded series may place more emphasis on early visits and result in incr eased DTP1-AA. rates and, ultimately, higher vaccination coverage rate s.